scholarly journals Influence of ocean-atmosphere coupling on the properties of tropical instability waves

2004 ◽  
Vol 31 (16) ◽  
Author(s):  
Luciano P. Pezzi
Keyword(s):  
Instability Waves ◽  
Tropical Instability Waves ◽  
Ocean Atmosphere

Tropical Atmospheric Variability Forced by Oceanic Internal Variability

2007 ◽  
Vol 20 (4) ◽  
pp. 765-771 ◽  
Author(s):  
Markus Jochum ◽  
Clara Deser ◽  
Adam Phillips
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Rainfall Variability ◽  
Circulation Model ◽  
Internal Variability ◽  
Tropical Pacific ◽  
Atmospheric Variability ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
The Tropical Pacific

Abstract Atmospheric general circulation model experiments are conducted to quantify the contribution of internal oceanic variability in the form of tropical instability waves (TIWs) to interannual wind and rainfall variability in the tropical Pacific. It is found that in the tropical Pacific, along the equator, and near 25°N and 25°S, TIWs force a significant increase in wind and rainfall variability from interseasonal to interannual time scales. Because of the stochastic nature of TIWs, this means that climate models that do not take them into account will underestimate the strength and number of extreme events and may overestimate forecast capability.

scholarly journals Deep Intraseasonal Variability in the Central Equatorial Atlantic

2018 ◽  
Vol 48 (12) ◽  
pp. 2851-2865 ◽  
Author(s):  
Franz Philip Tuchen ◽  
Peter Brandt ◽  
Martin Claus ◽  
Rebecca Hummels
Keyword(s):  
Intraseasonal Variability ◽  
Deep Ocean ◽  
Minor Role ◽  
Equatorial Atlantic ◽  
Near Surface ◽  
Velocity Fluctuations ◽  
Instability Waves ◽  
Vertical Mode ◽  
Tropical Instability Waves ◽  
Meridional Velocity

AbstractBesides the zonal flow that dominates the seasonal and long-term variability in the equatorial Atlantic, energetic intraseasonal meridional velocity fluctuations are observed in large parts of the water column. We use 15 years of partly full-depth velocity data from an equatorial mooring at 23°W to investigate intraseasonal variability and specifically the downward propagation of intraseasonal energy from the near-surface into the deep ocean. Between 20 and 50 m, intraseasonal variability at 23°W peaks at periods between 30 and 40 days. It is associated with westward-propagating tropical instability waves, which undergo an annual intensification in August. At deeper levels down to about 2000 m considerable intraseasonal energy is still observed. A frequency–vertical mode decomposition reveals that meridional velocity fluctuations are more energetic than the zonal ones for periods < 50 days. The energy peak at 30–40 days and at vertical modes 2–5 excludes equatorial Rossby waves and suggests Yanai waves to be associated with the observed intraseasonal energy. Yanai waves that are considered to be generated by tropical instability waves propagate their energy from the near-surface west of 23°W downward and eastward to eventually reach the mooring location. The distribution of intraseasonal energy at the mooring position depends largely on the dominant frequency and the time, depth, and longitude of excitation, while the dominant vertical mode of the Yanai waves plays only a minor role. Observations also show the presence of weaker intraseasonal variability at 23°W below 2000 m that cannot be associated with tropical instability waves.

scholarly journals Sensitivity of Pacific Ocean Tropical Instability Waves to Initial Conditions

2003 ◽  
Vol 33 (1) ◽  
pp. 105-121 ◽  
Author(s):  
Jérôme Vialard ◽  
Christophe Menkes ◽  
David L. T. Anderson ◽  
Magdalena Alonso Balmaseda
Keyword(s):  
Pacific Ocean ◽  
Initial Conditions ◽  
Instability Waves ◽  
Tropical Instability Waves

scholarly journals An Empirical Model for Surface Wind Stress Response to SST Forcing Induced by Tropical Instability Waves (TIWs) in the Eastern Equatorial Pacific

2009 ◽  
Vol 137 (6) ◽  
pp. 2021-2046 ◽  
Author(s):  
Rong-Hua Zhang ◽  
Antonio J. Busalacchi
Keyword(s):  
Wind Stress ◽  
Empirical Model ◽  
Stress Responses ◽  
Large Scale ◽  
Climate Models ◽  
Surface Wind ◽  
Microwave Remote Sensing ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
Sst Forcing

Abstract High-resolution space-based observations reveal significant two-way air–sea interactions associated with tropical instability waves (TIWs); their roles in budgets of heat, salt, momentum, and biogeochemical fields in the tropical oceans have been recently demonstrated. However, dynamical model-based simulations of the atmospheric response to TIW-induced sea surface temperature (SSTTIW) perturbations remain a great challenge because of the limitation in spatial resolution and realistic representations of the related processes in the atmospheric planetary boundary layer (PBL) and their interactions with the overlying free troposphere. Using microwave remote sensing data, an empirical model is derived to depict wind stress perturbations induced by TIW-related SST forcing in the eastern tropical Pacific Ocean. Wind data are based on space–time blending of Quick Scatterometer (QuikSCAT) Direction Interval Retrieval with Thresholded Nudging (DIRTH) satellite observations and NCEP analysis fields; SST data are from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). These daily data are first subject to a spatial filter of 12° moving average in the zonal direction to extract TIW-related wind stress (τTIW) and SSTTIW perturbations. A combined singular value decomposition (SVD) analysis is then applied to these zonal high-pass-filtered τTIW and SSTTIW fields. It is demonstrated that the SVD-based analysis technique can effectively extract TIW-induced covariability patterns in the atmosphere and ocean, acting as a filter by passing wind signals that are directly related with the SSTTIW forcing over the TIW active regions. As a result, the empirical model can well represent TIW-induced wind stress responses as revealed directly from satellite measurements (e.g., the structure and phase), but the amplitude can be underestimated significantly. Validation and sensitivity experiments are performed to illustrate the robustness of the empirical τTIW model. Further applications are discussed for taking into account the TIW-induced wind responses and feedback effects that are missing in large-scale climate models and atmospheric reanalysis data, as well as for uncoupled ocean and coupled mesoscale and large-scale air–sea modeling studies.

The Role of the NECC in a Strong El Niño.

2020 ◽  
Author(s):  
David Webb
Keyword(s):  
Ocean Model ◽  
Warm Water ◽  
Ekman Transport ◽  
Global Ocean ◽  
Instability Waves ◽  
Tropical Instability Waves ◽  
The North ◽  
Ocean Science ◽  
The Pacific ◽  
North Equatorial Counter Current

&lt;p&gt;An analysis of archived data from the NEMO 1/12th degree global ocean model shows the importance of the North Equatorial Counter Current (NECC) in the development of the strong 1982&amp;#8211;1983 and 1997&amp;#8211;1998 El Ni&amp;#241;os.&amp;#160; The model results indicate that in a normal year the coreof warm water in the NECC is diluted by the surface Ekman transport, by geostrophic inflow and by tropical instability waves. During the development of the 1982&amp;#8211;1983 and 1997&amp;#8211;1998 El Ni&amp;#241;os, these processes had reduced effect at the longitudes of warmest equatorial temperatures. During the autumns of 1982 and 1997, the speed of the NECC was also increased by a stronger-than-normal annual Rossby wave and other changes in sea level in the western Pacific.&amp;#160; The resulting increased transport of warm water by the NECC resulted in water with temperatures above 28C reaching the eastern Pacific.&amp;#160; This appears to have been a major factor in moving the centre of deep atmospheric convection eastwards across the Pacific.&lt;/p&gt;&lt;p&gt;Note:&amp;#160; This is based on the paper published in Ocean Science.&amp;#160; An oral presentation is possible.&lt;/p&gt;

scholarly journals SMOSSea Surface Salinity signals of tropical instability waves

2014 ◽  
Vol 119 (11) ◽  
pp. 7811-7826 ◽  
Author(s):  
Xiaobin Yin ◽  
Jacqueline Boutin ◽  
Gilles Reverdin ◽  
Tong Lee ◽  
Sabine Arnault ◽  
...  
Keyword(s):  
Surface Salinity ◽  
Instability Waves ◽  
Tropical Instability Waves
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